1. Field of the Invention
The present invention relates to tools and methods for disposing, coating, repairing, or otherwise modifying the surface of a metal substrate using frictional heating and compressive loading of a consumable metal against the substrate. Embodiments of the invention include friction-based fabrication tooling comprising a non-consumable member with a throat and a consumable member disposed in the throat, wherein the throat is operably configured such that during rotation of the non-consumable member at a selected speed, the throat exerts normal forces on and rotates the consumable member at the selected speed; and comprising means for dispensing the consumable member through the throat and onto a substrate using frictional heating and compressive loading.
2. Description of Related Art
Conventional coating techniques, such as flame spray, high-velocity oxygen fuel (HVOF), detonation-gun (D-Gun), wire arc and plasma deposition, produce coatings that have considerable porosity, significant oxide content and discrete interfaces between the coating and substrate. Typically, these coating processes operate at relatively high temperatures and melt/oxidize the material as it is deposited onto the substrate. Such conventional techniques are not suitable for processing many types of substrates and coating materials, such as nanocrystalline materials due to the grain growth and loss of strength resulting from the relatively high processing temperatures.
An alternative deposition process available is referred to as cold spray type depositing. Such techniques typically involve a relatively low-temperature thermal spray process in which particles are accelerated through a supersonic nozzle. These techniques, however, may be relatively expensive and/or generally incapable of processing high aspect ratio particles, such as nanocrystalline aluminum powder produced by cryomilling. As a result, products prepared using cold spray techniques typically contain oxide impurities.
In light of these drawbacks, improvements in coating deposition techniques are highly desired. Indeed, there is a specific need for friction-based fabrication tools capable of depositing coatings on substrates efficiently and in a simple manner, which result in high quality adhesions between the substrate and coating and high strength products having an increased resistance to failure.